Pheromone Disruption of Argentine Ant Trail Integrity

Abstract

Disruption of Argentine ant trail following and reduced ability to forage (measured by bait location success) was achieved after presentation of an oversupply of trail pheromone, (Z)-9-hexadecenal. Experiments tested single pheromone point sources and dispersion of a formulation in small field plots. Ant walking behavior was recorded and digitized by using video tracking, before and after presentation of trail pheromone. Ants showed changes in three parameters within seconds of treatment: (1) Ants on trails normally showed a unimodal frequency distribution of walking track angles, but this pattern disappeared after presentation of the trail pheromone; (2) ants showed initial high trail integrity on a range of untreated substrates from painted walls to wooden or concrete floors, but this was significantly reduced following presentation of a point source of pheromone; (3) the number of ants in the pheromone-treated area increased over time, as recruitment apparently exceeded departures. To test trail disruption in small outdoor plots, the trail pheromone was formulated with carnuba wax-coated quartz laboratory sand (1 g quartz sand/0.2 g wax/1 mg pheromone). The pheromone formulation, with a half-life of 30 h, was applied by rotary spreader at four rates (0, 2.5, 7.5, and 25 mg pheromone/m(2)) to 1- and 4-m(2) plots in Volcanoes National Park, Hawaii. Ant counts at bait cards in treated plots were significantly reduced compared to controls on the day of treatment, and there was a significant reduction in ant foraging for 2 days. These results show that trail pheromone disruption of Argentine ants is possible, but a much more durable formulation is needed before nest-level impacts can be expected.

Trail Pheromone Disruption of Argentine Ant Trail Formation and Foraging

“…This is an improvement in longevity of disruption over the wax-based dispersible formulating originally tested, which disrupted visual trails and foraging at bait cards in 4-m 2 plots for only 24 h (Suckling et al 2008). We also were able to demonstrate significant disruption of foraging by Argentine ant workers for bait cards.…”

“…Our bioassay that examined traffic rates proved to be a robust and reliable measure of trail disruption from a point source (Suckling et al 2008;Tanaka et al 2009). The results showed that the treated bioassay cards, stored in the absence of sunlight or rainfall, maintained their efficacy at disrupting trail following for many weeks.…”

“…In previous work, we quantified the integrity of Argentine ant trail-following behavior by video analysis of movement and track angles (Suckling et al 2008). Trail integrity, defined as r 2 for the position of ants in a video frame, was devised as a measure of the ability of workers to follow a reasonably straight trail, before and after the application of a point source of synthetic trail pheromone.…”

“…Well-formed trails were completely disrupted indoors by using a crude wax-based formulation. However, due to rapid pheromone release from the wax-coated quartz sand, only several hours of disruption was achieved in small (1 m 2 and 4 m 2 ) plots (Suckling et al 2008).…”

Alkylpyrazines: alarm pheromone components of the little fire ant, Wasmannia auropunctata (Roger) (Hymenoptera, Formicidae)

“…For detection, pyrazine lures may have advantages over the commonly used peanut butter baits in that they may be more species-specific, longer lasting, more easily packaged, mess-free in application, and less prone to spoil. Potential control applications of W. auropunctata pheromones include use in insecticidal baits to increase feeding (Hughes et al, 2002) and direct disruption of ant behavior, similar in concept to pheromone mating disruption (Suckling et al, 2008). Further testing in the field will be required to assess the potential of these possible applications.…”